Brace



March 3l, 1942.

BRAcE Filed April 15, 1939 F. E. DETMERsn' TTORNEY Patented Mar. 31, 1942 UNTE S'ATE ATEN'" FHQE 6 Claims.

This invention relates to braces for holding, directing, and turning tools such as bits, taps, screw drivers, and the like, and more specifically contemplates a Atool holding and turning device embodying a manually-operable crank having a variable throw.

Conventional braces of the prior art usually include a chuck at one end for releasable engagement of the tool to be operated, and a rotatable directional control handle on its opposite end, the chuck being rotated by a cross bar or crank rigidly connected in such device between the chuckand the handle. The distance between the axis of the chuck and the handle on the crank is fixed in suchl devices, thus determining the diameter of the circle described by the crank in operation, and thereby establishing a xed ratio between the speed and power which may be applied to the tool. Due to the provision in such devices of the separation of the means for rotating and guiding the tool, respectively, the user is required to use both of such means, necessitating the use of both hands, in the controlled operation thereof. The length of such braces, and thexed circle of movement of the crank, requiring, in operation, a lateral disposition and reciprocation of the arm of a user, renders such devices cumbersome, and in many instances, of no utility at all in restricted areas.

A principal object of the present invention is to provide a hand-operated brace embodying a chuck adapted to receive and engage tools of various well known general types, and incorporating a single handle oiset with respect to the axis of the chuck and tool by which the tool may be both rotated and directed.

More specifically, an object is the provision of a tool `holder 4having a crank arm carrying an operating handle and incorporating a variable connectionl between the crank arm and chuck to adjust the throw of the handle.

Another and highly important object of the invention is to provide a tool holder having a handle connected thereto by means of an arcuate cross arm, the axis of the handle and tool-holding chuck forming an acute angle having its vertex at the center of the arc of the cross arm and disposed rearwardly of the butt of the handie, i. e., at a point substantially coinciding with the center of the wrist joint of a user with the latter holding the device in normal operating position with the butt of the handle in the palm of his hand:

Another object is to provideva chuck embody- `ing a singlerotatable member adapted in operation to simultaneously clamp a tool between the jaws thereof and secure the cross arm of the crank handle in any adjusted position.

Another object is the provision of a brace having all or selected combinations of the features above indicated and including a pair of chucks separated by an extension which furnishes a bearing for an auxiliary handle to facilitate directional control and enable the application of greater pressure to the tool.

Another object is to provide means to releasably secure a screw driver bit in the brace with the cross arm of the brace extending from the axis of the driver substantially ninety degrees from the plane through the screw engaging edge of the driver to minimize tendency of the driver to slip out of the nick in the head of a screw upon the application of rotary force to the brace in either direction.

Other objects and corresponding advantages, such, for example, as simplicity of construction, operation exclusively by the wrist motion of the user to facilitate its manipulation in restricted areas, yet enabling great pressure to be applied to the tool when desired, and a handle mounting both durable and economical of manufacture and assembly, will be apparent to those of skill in the art from an examination of the following description read in the light of the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional View of one form of my invention illustrating particularly its application as a drill brace;

Fig. 2 is a reduced elevation of a simpleembodiment of the device depicting the angular relationship of the iiat sides of the end of a screw driver with respect to the handle of the brace;

Fig. 3 is a reduced elevation similar to Fig. 2 illustrating a tapv chuck in operative relation therewith;

Fig. 4 is an enlarged fragmentary section of the chuck and handle showing in dotted lines the relation therebetween withvthese parts arranged to provide a dilerent throw of the crank arm;

Figs. 5 and 6 are vsectional views taken on correspondingly numbered lines of Fig. 4;

Fig. 7 is a broken elevation of one of the jaws of the chuck illustrating the novel form of thread thereon.

Referring to the drawing in detail, the numerals of which indicate similar parts throughout the several views, and with particular reference tc Figs. 4 6, Il! designates generally a chuck comprising a tubular member l I having anintegral head l 2 of larger diameter closing one end of the member. The tubular member II is slotted through diametrically opposite sides as at I3 from points adjacent the head through the opposite tool-receiving end of the chuck. The two sections of the member thus separated comprise flexible clamping jaws I4 forming a circular bore I5 of the tubular member, which bore extends toward the head a sufficient distance to insure positive frictional engagement of the stem I6 of a tool inserted therein. Rearwardly of the circular bore I5, the member and head are slotted as at I1 through opposite sides thereof on a plane forming a right angle with the plane through slots I3. Slot I'I is in communication with the bore I5, and is of a width slightly less than the diameter of bore I so as to form a pair of internal shoulders I8 at the inner end of said bore.

The round stem I6 of the tool, or other member which the chuck is adapted to engage, has a sliding lit with bore I5. The end of the stem is formed with two flat parallel surfaces I9 adapted upon insertion of the stem into the bore to have a sliding t with the walls forming the slot I'I in the tubular member. It will be observed that in the case of a screw driver bit, the flat surfaces I9 thereof are disposed at a right angle with the flattened end of the driver head 20 for a purpose later referred to. Shoulders 2| formed on the end of the round portion of the stem adjacent the flat surfaces I9 abut against the internal shoulders I8 of the chuck when in operative relationship therewith to limit the extent of the stern into the chuck. With the shoulders I8 and 2| in contact with one another, the adjacent end of the stem will terminate within the portion of slot I'I in advance of the head I2.

In order to rotate the chuck, a crank is provided comprising an arcuate cross arm 22 which is rectangular in cross-section and of a thickness suoient to have a sliding t with the slot II. The width of the cross arm is slightly greater than the length of the portion of slot II in head I2. A shaft 23 is integrally connected to one end of the cross arm 22 to furnish a handle mounting hereinafter more specifically de scribed. The cross arm 22 is inserted in the slot I'I filling the portion thereof in the head I2 and extending slightly into the portion of slot I'I in the tubular member. The cross arm is held at any adjusted degree of extension therein, by means comprising a washer 24 slidably mounted on the tubular member II. One end of a helical spring 25, encircling the member, bears against washer 24. A collar 26 is slidably mounted on the member to contact the opposite end of spring 25. 'I'he member is externally threaded as at 21 to receive a knurled nut 28 adapted upon rotation to compress spring 25 by moving the collar 26 thereagainst, and thereby urge the washer 24 into frictional engagement with the edge of the cross arm 22 passing through slot I'I in advance of the head I2. With the cross arm clamped between the end of slot I1 in the head and the collar 26, further rotation of the knurled nut 28 will be resisted by the collar, tending to cause the nut to ride up on the threads 21 of the tubular member which, in turn, forces the jaws I4 of the chuck into clamping engagement with the portion of the tool stem disposed between the jaws. To insure a more positive grip on the tool stem the side 29 of each thread on the member, which is engaged by the nut 28 as the latter is tightened, forms a 45 angle with the axis of the member, whereas the opposite sides 36 of the threads and the axis of the chuck form 75 angles. By thus providing a broader surface on the rearward side 29 of each thread for engagement by the nut, a more gradual tightening of the jaws on the tool stem is made possible, which reduces the tendency of the nut to strip the threads.

The shaft 23 and cross arm 22, comprising the crank, form an acuate angle therebetween whereby the angle formed between the axis of shaft 23 and the chuck, respectively, will have its vertex slightly rearward of the butt of the handle 3|, journalled on the rod, i. e., at a point which will substantially coincide with the center of the wrist joint of the user when holding the handle in the palm of his hand. It is also important that the arc of the cross arm 22 have its center on the vertex of the angle between the axis of the handle 3| and the axis of the chuck in order to maintain a constant vertex of the variable angle formed between the last-named parts throughout the range of sliding adjustment of the cross arm in slot I'I of the chuck.

The shaft 23 is formed with a ball bearing cone 32 integral with the shaft, cone 3'2 being grooved as at 33 for the retention of a plurality of bearings 34. The wooden handle 3| is pressed on a sleeve 35 which provides a bearing for shaft 23. The sleeve 35 is bellcd at its outer end to form a race 36 for bearings 34 and to receive the cone 32 of the shaft. A ferrule 31 is secured by suitable means over the end of the handle in which the bearings are located after assembly of the parts above mentioned to retain the sleeve and handle on the rod.

The embodiment of Fig. 1 incorporates additional features particularly adapted for use as a drill brace. The stem 38 which is engaged by the chuck carries an enlarged threaded portion 39 at the opposite end, on which is mounted a conventional type auxiliary drill chuck 40 for a drill 4|. A handle 42 slidably and rotatably encircling the stem 38 between the chucks I0 and 40, carries a thrust bearing 43 in its forward end adapted to bear against the adjacent end of the threaded enlargement 39 of the stem. The utility of the handle in facilitating the application of additional pressure to the drill will be obvious to those of skill in the art.

In Fig. 3, the brace of my invention is illustrated as engaging a stem 43 carrying at its outer end a tap chuck 44 of conventional design.

While I have described the embodiment of Fig, 1 as particularly adapted for operating a drill, it will be apparent that such additional apparatus may be employed with any of the numerous tools requiring rotary motion in operation, to which my invention is adaptable.

It will be observed that I have provided a brace which may be operated most effectively by the wrist motion of the user, and incorporating an adjustable connection between the handle and tool to vary the throw of the handle whereby the leverage on the tool may be changed to meet specific requirements.

While I have illustrated and described a simple preferred embodiment of my invention, it will be understood that numerous changes may be made in size, design, number, and proportion of the various parts; that the rotatable mounting for the handles 3| and 42 may be of any other form well known in the art; that a ratchet connection may be provided in the chuck to enable rotation of a tool held thereby without a complete revolution of the handle, as will be obvious, and further, that an adjustable pivotal connection between the cross arm and rod on which the handle 3| is mounted may be substituted for the integral connection between these parts specically illustrated-all without departing from the spirit of my invention as defined by the appended claims.

What I claim and desire to secure by Letters Patent is: f

1. In a brace, a chuck having a circular bore communicating with a slot through opposite sides of one end of the chuck, a rotary tool extending into the bore of the chuck and engaged by the latter, a cross arm extending through said lastnamed slot, a handle connected to one end of said cross arm, a nut threaded on said chuck, and means actuated by said nut to secure said cross arm at a selected position in said slot.

2. In a brace, a chuck comprising a pair of jaws, a rotary tool extending into the bore of the chuck and engaged by said jaws, a head integral with said chuck having a slot therein, a cross arm extending through said slot, a nut threaded on said jaws to close the same by rotation of said nut, means including a resilient element intermediate said nut and head to secure said cross arm in said slot.

3. In a brace, a chuck comprising a pair of jaws, a rotary tool adapted for engagement by said jaws, a head integral with said jaws at one end of said chuck, a crank associated with said head having a variable throw, means including a member operable in response to rotation thereof to close the jaws of said chuck and releasably iix the throw of said crank.

4. In a brace, a chuck comprising a pair of jaws, a rotary tool releasably engaged in said chuck by said jaws, a crank arm comprising an arcuate member and a handle member forming an angle therebetween, means associated with said chuck to grip the arcuate member at any point on its length to x the angle between the axes of said chuck and said handle member, respectively, the arc of said cross arm having its center on the vertex of the angle formed between the last-named axes.

5. In a brace, a chuck, a rotary tool releasably engaged by said chuck, a crank comprising an arcuate member and a handle member forming an angle therebetween, means to slidably receive said arcuate member associated in said chuck whereby the axes of the chuck and handle member form e variable acute angle, said angle having a vertex rearwardly of the handle member, the arc of said arcuate member having its center coinciding with said vertex.

6. In a brace, a chuck comprising a pair of jaws and e head having a slot therein, a rotary tool releasably engaged in said chuck by said jaws, a cross arm extending through said slot, means encircling said chuck adapted to bear against said cross arm, a nut threaded on said chuck, and a spring intermediate said means and said nut to urge, upon compression by said nut,

said means into engagement with said cross arm.

FRED E. DETMERS. 

